This invention is an improvement to my prior invention covered by U.S. Pat. No. 4,673,937 and provides an enhancement thereto. The invention relates to radar devices and more particularly to an expert system for continuously and dynamically monitoring the headway between a vehicle and a stationary or moving object of immediate concern based on a practical driving mathematical formula or algorithm.
Preferably a vehicle radar system should always alert the driver in time to avoid a collision. However, in real-world traffic situations, this is not always possible. Curving roadways, cross traffic, and many other fast-changing situations make it physically impossible in many situations for the radar to always give the driver the time and distance needed for stopping. But alerting the driver just one second (e.g. 73 feet at 50 MPH) before impact can often provide enough time to steer around an obstacle, or at least allow some additional braking time. The system can provide seconds in many situations that may give drivers the extra time they need.
Some of the safety benefits a vehicle radar system can provide are:
Radar will be constantly on guard to act as a safety back-up for distracted drivers.
Radar should prevent many sideswipe accidents, especially when the road is straight or turns left.
Radar can help drivers establish and maintain safer driving margins in traffic situations.
Radar can respond very quickly in accident situations to alert drivers.
Radar, to be truly effective, must perform well enough to gain the driver's confidence. To be most effective and meaningful for a driver, the system should communicate in the same manner as a passenger would warn an unsafe driver. A passenger knows when a driver is unsafe and he will respond accordingly. If a driver is careless, a passenger may say something; if a collision is imminent, he may yell. The radar warning system should also communicate its measured level or interpretation of the hazardous situation and alert the driver in words and statements. The system can now say "look out", "be careful", and alert the driver in appropriate situations.
The primary control for vehicle safety will always be in the hands of the driver. However, when a driver is not paying attention, the radar will be working for him in many critical situations. This means it should not miss too many opportunities to avoid preventable accidents; yet it must not disturb the driver or passenger needlessly. Therefore, the output of the radar warning system should be focused toward keeping the driver attentive in hazardous and dangerous situations and alerting him to take action.
The complex, moving environment the vehicle radar sees, and must operate in, poses many difficulties for reliable and optimum system performance. With a small high-gain antenna mounted two feet above the roadway, many nearby objects must and will be seen by the radar system. Radar energy bounces around when it hits nearby objects, much like water from a nozzle would bounce back from a nearby object. A sensitive radar will see the road, cars, posts and any other nearby and distant objects in the radar beam. Some small, poorly shaped radar objects (referred to as targets) are hard to see. Other targets are very large, and some large targets can be seen miles away. The necessary dynamic operating range of the system must, therefore, be great to see both small and large targets. Many vehicle radar systems can only see or respond to larger targets at close range. A good short-range radar system must detect smaller targets and also work well when large targets are blindingly close. A radar can blind itself by its own return.
All of these environmental difficulties are manifested one way or another as signal problems such as distortion, saturation, multipath, multitarget, multibounce, and multiple returns. Other related problems are false alarms, radar blinding, electrical interference, road noises, vehicle noise, bounce and vibration, weather, and similar phenomena.
These environmental problems are some of the primary reasons why vehicle radar has been such a challenge to develop. Regardless of environmental restrictions, it is very important for a system to recover all the information available in the radar signal. The difficulties of extracting the information from a weak, saturated or distorted return signal have caused vehicle radar designers to look for alternate solutions.
The road performance of the vehicle radar antenna and the circuits that back it up must be very good in order to see smaller radar targets. The major factor in any vehicle radar system will be how well the radar sees and recognizes the weaker targets. Some objects, at times, appear almost invisible to the radar. The normal signal strength range or radar cross-section of these radar returns now varies about 50 DB. Some poor radar targets can be improved with ease, but detecting a small child will always be a challenge for any radar system.
Roadways are now enhanced with all types of visual aids to help the driver's vision. Radar visibility can also be enhanced by adding a radar reflecting device or material to existing vehicles and roadside markers. Visible light and radar images are comparable in many ways. Radar returns respond somewhat like looking at yourself in a mirror. A slight turn of the mirror and you image disappears, even though you can still see the mirror. Radar returns don't suddenly disappear like the visual image, but they do become very weak in many cases.
As vehicle radar becomes a reality, vehicles may have improved radar cross-sections, or they may be augmented with one or more radar reflectors to enhance their radar image. It takes a very small change to make poor radar targets many times stronger, especially at higher frequencies. A radar system should still be able to perform in the present automotive environment. However, when the roadway environment is improved for radar, it will be better for drivers as well.
The invention described and claimed in the '957 patent advanced the art of vehicle safety by a quantum leap and has been successfully tested under actual working environments to enhance the safety of vehicle travel by alerting the driver of that vehicle to headway dangers when the driver is distracted or otherwise unaware of impending danger of impact with an object either moving at a slower speed than the radar equipped vehicle or a stationary object of concern in the path of the radar equipped vehicle.
U.S. Pat. Nos. of interest that were cited in the prosecution of my prior patent above mentioned are as follows: 3,153,230 issued to Van Krevelen et al. in October 1964; 3,383,678 issued to Palmer in May 1968; 3,698,882 issued to Dessailly in September 1972; 3,725,921 issued to Weidman et al. in April 1973; 3,778,826 issued to Flannery et al. in December 1973; 4,366,546 issued to Tachibana et al. in May 1983.
The design for vehicle radar starts with a good antenna and microwave system that can detect small, complex targets. The antenna beam has to be sized, shaped and steered appropriately to cover a vehicle's changing headway. The detected signal is usually distorted as a result of complex multitarget returns. the signal, however, contains all the needed information such as closing rate, range, direction, signal coding, interference, and other data needed by the radar system.
Assuming that we have all the radar data, it must be conditioned and processed to determine how many feet (or seconds) a driver needs for accident prevention. Then the radar's external information is combined with the vehicle's internal data components (vehicle speed, steering, acceleration, stopping, etc.) plus the driver inputs to have all the inputs to make the radar system operational. The internal vehicle and driver inputs are referred to as driving monitors or driving modifications (DMs), which describes their function. If a radar system were in free space looking at a target ten miles away, no system modification would be necessary. However, in the ever-changing vehicle radar environment, where small and large objects are constantly passing nearby at various speeds, a different solution was needed and developed. The vehicle radar system design of this invention was adapted to the environment as well as to the vehicle usage.
Once the radar, vehicle and driver inputs are available, they are conditioned and then combined in a digital analog processor. After this data is in the microprocessor, the system can be programmed to fit the vehicle's driving situation to achieve the appropriate outputs for the driver.
The main output of the vehicle radar system is to alert the driver--who is the vehicle's ultimate safety device. The radar warning system is designed to keep the driver safer and to actively warn him in dangerous situations.